Some games are completely proprietary- they show components and game play, but the exact rules, cards, and pieces are not given until a person buys it. My instinct is to follow this model. However, there is another way.
Other games provide a free PDF download of the rules, and some even give a Print and Play (PNP) version. At first blush it seems like this is giving away the keys to the kingdom. Why would someone buy a game they can play for free? And what's to stop someone from taking all your hard work and coopting it as their own?
Aside from these reservations, there are clear advantages to the free and open model. When considering whether to back a game, people are more likely to do so if they have more information. If I have little way of knowing whether I'll like a game, it's less likely I'll be willing to put money down on it.
With these considerations in mind, I think I've found a middle road for Archon Arena. The game consists of 42 combat cards divided into 3 decks at play time. In addition, there are 5 posture cards and 6 leaders. My idea is to provide a PNP version with enough cards to play one battle. So rather than all the cards, I'd have a version with just 14 combat cards, the postures, and 2 of the leaders. This would be enough to give people a taste of the rules and game play without giving everything away. I'd also include just the info on the cards, not the artwork, so there is added incentive for people to buy the full game.
While it seems that free and open and proprietary are mutually exclusive alternatives, I'm hoping that this middle approach can give the best of both worlds. Maybe it will work for you too.
Thanks to Artrimis on TGC for inspiring this post.